Patent GB-272000-A (GB)
Title: Driving and stopping mechanism
IPC: D05B69/22
Filed: 1926-04-17
Abstract: 272,000. Fairweather, W., (Singer Manufacturing Co.). April 17, 1926. Starting and stopping gear. - In a high-speed sewing-machine, means controlled by a timing device driven by the machine shaft are provided for moving the driving belt from a fast to a loose pulley after a predetermined number of rotations of the shaft, and the action of a positive stop mechanism adapted to bring said shaft to rest in a predetermined angular position is initiated by a second timing mechanism after the belt has been moved on to the loose pulley. The invention is described as applied to a buttonhole sewing-machine having fast and loose belt pulleys 40, 39 mounted on the main shaft 9, and a vertical shatt 33 carrying a feed wheel 28 having cam grooves 27, 32 engaged by levers 25, 29 actuating the slide plates 17, 22 of the work holder, the shaft 33 being driven from the shaft 9 by gearing 35, 37, 38. A lever 45 pivoted at 46 on a bracket 47 carries a spring- pressed plunger 44 adapted to cooperate with a cam 41 on the shaft 9 having a notch 43 so as to stop the shaft in a predetermined angular position. An arm 50 projecting from the lever 45 is connected to a rod 51 formed with a notch 52 adapted to engage a spring-pressed lever 53. The lever 53 carries an adjustable tripping point 54 adapted to be engaged in a tripping point 55 on the wheel 28. A belt fork 57 is secured to a rod 58 slidable in spaced bosses 59 on a lever 60 pivoted at 61, the other arm 62 of the lever carrying a tripping point 63 adapted to be engaged by a tripping point 64 adjustably mounted on the inner face of a wheel 34 mounted on the shaft 33. A spring 68 tends to maintain the lever 60 in engagement with an adjustable abutment screw 69. A collar 70 secured on the rod 58 between the bosses 59 tends to be maintained in engagement with one of the bosses by a spring 71. A pin 76 carried by an arm 56 extending from the lever 45 is adapted to engage a tooth 74 on a block 73<1> fixed to the rod 58. To start the machine the lever 45 is tilted so as to disengage the plunger 44 from the cam 41. whereupon the lever 53 snaps into the notch 52 and action of the pin 76 against the tooth 74 forces the rod 58 to the left. thus moving the belt b @ocks the lever 45 in tilted position, and the action of the pin 76 against the tooth 74 forces the rod 58 to the left thus moving the belt b from the loose to the fast pulley. Just prior to the completion of the sewing operation, the point 64 tilts the lever 60 to release the block 73<1> from the pin 76, whereupon the spring 78 urges the rod 58 to the right, thus moving the belt to the loose pulley 39. The machine runs under its own momentum in sewing the final stitches until the point 58 tilts the lever 53 to release the lever 45. which is then swung into vertical position by a spring 48 and stops the shaft. During this movement of the lever 45, the pin 76 rides over the inclined surface 75 of the block 73<1> to reengage the tooth 74. The machine is provided with a control shaft 77 actuated from a continuously-running pulley 78 through a partial rotation clutch mechanism including a driven disc 79 carrying two angularly-shaped radiallyslidable clutch dogs 80 with which the clutch controlling lever 81 co-operates to effect a coupling of the shaft 77 to the pulley 78 for a partial rotation prior to starting the machine proper and also after stoppage of the machine proper, the first partial rotation serving to close the work clamp 21 and, through a cam 82 and link 84, to tilt the lever 45 for starting the machine. A treadle is connected with a lever 85 which engages the lever 81. Specifications 225,748 and 226,133 are referred to.